Direct fired water heater

ABSTRACT

A direct fired water heater comprising a rotary drum, a water inlet and a water outlet therefor, a burner generally centrally located in the drum, the burner being fixed, there being an inlet stator and an outlet stator having openings at different distances from the inner periphery of the drum providing a static pressure difference in the water.

[191 [1 3,786,798 Huettner Jan. 22, 1974 4 [5 1 DIRECT FIRED WATER HEATER FOREIGN PATENTS OR APPLICATIONS [761 Invent: Huetmer, Inter 922,105 1/1955 Germany 122/11 Continental Corp., 193 W. Boylston west Boylston Mass 01583 Primary ExaminerWilliam F. ODea 22 Filed; 2 7 Assistant Examiner-William C. Anderson Attorney, Agent, or FirmCharles R. Fay [211 App]. No.: 228,290

[57] ABSTRACT [52] US. Cl 126/350 R A direct fired water heater comprising a rotary drum, [Sl Int. Cl. F24h l/l0 a water inlet and a water outlet therefor, a burner gen- {58] Field of Search 126/360 A, 360 R, 350 R; erally centrally located in the drum, the burner being 60/3957; 122/11 fixed, there being an inlet stator and an outlet stator 1 having openings at different distances from the inner [56] References Cited periphery of the drum providing a static pressure dif- UNITED STATES PATENTS ference in the v 7, 2,169,601 8/1939 Cornelius et al 122/11 11 Claims, 1 Drawing Figure ROTAT 1 ON DIRECT FIRED WATER HEATER BACKGROUND OF THE INVENTION Conventional water heaters are ordinarily character ized by the feature that the water to be heated and the products of combustion emenating from the flame are separated by a wall of some kind. The wall may be in the form of tubes or merely a container of any shape which is heated by hot combustion products passing over or along the same and heating the water by conduction.

Another conventional method of heating water resides in the injection of cold water into a flame, preferably gas, thereby heating a fine spray of water very rapidly due to the contact with the flame. This has decided disadvantages however: great care must be taken to inject the water at a point where the flame is not cooled to the point of incomplete combustion; some of the finer droplets may be readily turned into steam which must be recondensed so as not to be lost through the chimney effluent, and separation of the flue gas from the water vapor requires elaborate condensing devices. Therefore, much of the inherent simplicity of such a system is negated by the necessity for elaborate ancillary equipment.

SUMMARY OF THE INVENTION The present invention takes advantage of the extremely high heat transfer rates possible by direct contact between the water and flame using a cylindrical water surface.

There is no water injected into the flame and therefore there is less chance of vaporizing a part of the water but instead a rapidly rotating drum is provided with a water inlet, the water by centrifugal force forming a cylindrical water ring or wall at the interior of the drum. A fixed fuel burner extends into the center of the drum and the flame bears at least in part upon the inner surface of said ring or wall of water. The diameter of the water ring is controllable while constantly adding water and extracting it at the same time it is being heated through direct contact with the flame; and this is done by providing an inlet and an outlet stator at different distances from the interior surface of the drum but both having openings directly into the water ring, thereby providing a differential of static pressure which is easily measured and can be used to control the inlet and outlet of the water.

The FIGURE in the drawing is a cross sectional view through a direct fired water heater according to the present invention.

PREFERRED EMBODIMENT OF THE INVENTION A hollow cylindrical drum I is provided, this drum containing a series of circumferentially spaced inwardly directed longitudinal baffles indicated at 12, together with circular baffles 14 having interruptions or apertures 16 therein for the passage of water therethrough. The drum is closed at its ends by top plate 18 and by the bottom plate 20. Plate 18 is connected to a hollow shaft 22 mounted on bearings 24 internally thereof and the shaft is provided with means such as a pulley 26 by which it is rapidly rotated by a motor not shown.

The bearings 24 are mounted on a fixed tubular member 28 which in turn mounts an inner tubular member 30, the latter in turn mounting the burner 32 with a burner face 34 and also an ignition means 36. Outside tube 30 there is an annular water inlet generally indicated at 38, the latter being derived from a pipe not shown through the inlet 40. Various seals may be utilized such as felt gasket 42 and others to prevent leakage, etc.

Bottom plate 20 carries an inverted frusto-conical open-ended member generally indicated at 44 which rotates therewith. This is provided with a series of openings only one of which is shown at 46, this having a vane 48 and a rectangular outstanding rim 50 directed inwardly of the conical member 44. In stopping the burner and drum, water may collect in the bottom of an encompassing housing 52 as in the area at 54 but on start up, this water is sucked back up into the drum by the conical member 44 at least to such a degree as to constitute substantially a complete transfer of such water into the drum.

There is a fixed inlet stator which is generally indicated at 56 and an outlet stator generally indicated at 58. These stators each comprise essentially a pair of circular plates having a space between them except for a number of curved vanes in the fashion of a closed centrifugal pump inpeller. The diameter of the inlet stator is greater than the diameter of the projected water level which is indicated at 60, and the outlet stator is constructed the same but the diameter of the outlet stator is greater than that of the inlet stator approaching closer to the wall of the drum [0 and farther into the water ring.

The hot water outlet comprises a series of tubes generally indicated at 62 leading into collection chamber 64 and water may be drawn off through the opening 66 as desired. The reference numeral 68 indicates a supporting bracket for the entire device which in general is suspended from a plate 70 which can be mounted on the bracket or by any other means desired.

The housing 52 may be utilized as a flue passage in the area at 74 between the drum and the inside wall of the housing and this exhaust for the flue gases 76 may take any form desired but it is to be realized that the housing 52 is fixed and the drum 10 rotates therein in spaced relation with respect thereto.

If a certain volume of water be admitted to the drum while it is spinning, a water ring or wall of cylindrical nature is formed having an inner surface at e.g., the indicated water level 60. The mass of the water ring or wall is subject to a centrifugal force which causes an increasing static pressure within the water ring or wall in a radially outward direction. Therefore at a given speed of rotation the static pressure within the water increases radially outwardly as the square of the radius. At the stated diameter of the inlet stator, the static pressure within the rotating water is substantially higher than the barometric pressure acting on the surface of the water level. Since the inlet stator is station ary, it is clear that if water is admitted to the water inlet, and to the hollow space connecting it with the inlet stator, at a static pressure equal to the static pressure surrounding the periphery of the inlet stator, both pressures are in balance and no water would flow either into or out of the rotating drum. At the same time the diameter of the water level inside the rotating drum would of course not change.

The static pressure within the water ring is greater at the outlet stator than at the inlet stator and water will be pumped out of the outlet stator as long as the water outlet 66 is open to the atmosphere. If now the outlet water flow were to be shut off by means of a valve, a static pressure is built up within the spaces between the outer periphery of the outlet stator and that valve which would be equal to the static pressure surrounding the periphery of the outlet stator. Again, no water would flow through the drum and the water level would remain at its prescribed diameter; but as the outlet valve is again opened, water is pumped out of the drum by the outlet stator which causes the water level to recede in a radially outward direction. Through this action, the static pressure surrounding the inlet stator at its outer periphery also decreases causing the higher static pressure of the water supply connected to the water inlet to feed water into the drum at a rate exactly equal to that rate at which water is pumped out of the drum by the action of the outlet stator.

As long as water is being pumped through the drum in the described manner, the static pressure conditions around the peripheries of both the inlet stator and the outlet stator are of course somewhat more complex owing to the fact that, in addition to the static pressures mentioned, there are also certain dynamic forces involved. In other words, the static pressure present in the inlet, or supply, side drops somewhat due to its conversion into dynamic head required for the flow to occur, but a similar condition also results at the point where the water is forced into the outlet stator not only by its static pressure but also by the dynamic energy imparted to it by the rotation of the drum. It is for this reason that both stators are internally equipped with curved vanes; those in the inlet stator being curved towards the direction of rotation, and those in the outlet stator being curved in the opposite direction against the direction of rotation so as to scoop the water into the outlet stator, thus taking advantage of the waters velocity head in pumping it out of the drum and into the outlet piping. By applying well-known principles in fluid dynamics the designer can readily minimize flow losses and irreversible energy conversions within the system.

The gas burner is an integral part of the inlet stator assembly. At the top of the unit provisions have been made for the admission of gas and air to the burner. Slots admitting air are provided with a shutter which allows adjusting the amount of combustion air being drawn into the burner proper. The necessary draft is provided by blower vanes attached to the conical extension of the bottom end plate whose suction effect draws the combustion air as well as the gas through the burner intake pipe and through the burner face. This burner face is made of alternating strips of corrugated stainless steel strip and plain strip wound around a core which also holds the ignitor electrode. Ignition of the gas/air mixture egressing from the burner face is accomplished by an electric spark jumping from the insulated dished ignitor head to the burner face windings. The resulting flame releases the heat of combustion within the hollow space formed by the rotating water level. Radiation emenating from the flame, as well as conducted heat from the products of combustion, is transmitted directly to the rotating water level, thus heating the water on its way through the drum. After having been cooled through contact with the water level, the flue gas passes through the open center of the outlet stator and is sucked through the open spaces between the transfer tubes into the blower wheel. From here it passes through the openings cut into the conically shaped blower wheel into the space between the outside diameter of the drum and the cylindrical housing. On its way up around the outside of the drum, the flue gas gives off more heat to the drum surface and, finally, exits through the spiral-shaped exhaust housing into the flue pipe.

To shut down the heater, power to the drive motor is shut off. A solenoid valve e.g., in the water supply line also closes with the shut-off of power and the drum coasts to a stop. As the speed of rotation of the drum decreases, a point is reached where the centrifugal force is no longer adequate to maintain the water ring inside the drum, the water ring collapses and the water flows through the conical blower wheel into the space formed by the bottom part of the housing and comes to rest. The gas supply also is shut off by e.g., a solenoid valve which is de-energized as the power supply to the motor is shut off.

If, after a shut-down as described above, the unit is restarted, the drive motor is energized and the rotation of the drum causes the inverted cone-shaped blower wheel to carry the water contained within the bottom part of the housing up into the drum. The longitudinal baffles inside the drum make sure that the water again forms a rotating water ring as before. It should be noted that the cone-shaped blower wheel serves two functions:

1. it provides for the necessary draft to suck the combustion air into the burner, and 2. its cone shape makes it act as a pump to carry water contained in the housing at stand-still into the drum as soon as rotation of the drum commences. To prevent water from being sucked through the openings in the cone by the action of the blower vanes, these openings are provided with the interior ridges 50. Therefore, only the flue gas emenating from the flame passes through the blower vanes while the housings water content is pumped up into the drum upon start-up. Since a certain clearance is required between the rotating cone-shaped blower wheel and the stationary housing, a certain amount of water will remain in the housing but will evaporate as it is heated by the flue gas passing over it, and the resulting water vapor will pass out the exhaust together with the flue gas.

This water heater does not require the use of shaft seals of any kind to convey water from a stationary member (the inlet stator) into the revolving drum, or to convey the water from the revolving drum into another stationary member (the outlet stator). The unique principle to balance a static pressure in a stationary member by the static pressure built up within a rotating water ring, as described above, lends itself to a multitude of applications other than the present invention. Applications of this principle in the areas of liquid-cooled gas turbine rotors, speed sensing devices, seal-less pumps, or heated pumps, etc. suggest themselves.

The two circular baffles shown on the cross-sectional drawing serve not only to space the longitudinal baffles, but also are provided with a number of holes to force the water flowing from the inlet to the outlet stator into an irregular flow pattern. The reason for this is that as the water ring is being heated near its surface, the heated water tends to stratify owing to the fact that warmer water becomes lighter than colder water, i.e., its specific weight is lower with an increase in temperature. Being subjected to centrifugal force, the warmer, lighter water would have a natural tendency to stay near the surface of the water ring while the colder, heavier water would be centrifuged out towards the inner wall of the drum. If such stratification were permitted to happen, the surface water would quickly reach the boiling point and turn into steam. The circular baffles are provided to prevent this stratification from occurring. Through their irregularly spaced holes the water is forced to mix, which results in a more uniform temperature distribution throughout the water ring. it should also be noted that there is also some heat transferred from the flue gas surrounding the drum on its outside through the drum itself, which would heat I the water near the drums inside wall. The resulting warmer water would also tend to flow towards the inside owing to its reduced specific weight, thus causing some circulation in a radial direction within the water ring. Taking these natural circulation patterns into account, it is easy to control the mixing of hot and cold water, together with a judicial adjustment of water flow rates through the unit, to achieve optimized performance without actually turning part of the heated water into steam.

I claim:

1. A liquid receptacle comprising a rotary cylindrical drum, said drum comprising a wall, closures for the drum at each end of the wall, means to rotate the drum, a liquid outlet and a liquid inlet for the drum, an inlet stator in the drum between the axis of the drum and the wall thereof, an outlet stator in the drum between the axis of the drum and the same wall thereof, the stators being open at their peripheries to provide for flow of liquid there-through; the outlet stator periphery being closer to the wall than the inlet stator, the rotation of the drum causing liquid in the drum to form a ring along the drum wall, the stators being normally submerged at their outer peripheries within the ring of liquid, a fuel burner in the drum, the burner being arranged to project a flame at least partially-directly against the ring of liquid.

2. The receptacle of claim 1 including a blower wheel on the drum adjacent the outlet.

3. The receptacle of claim 1 wherein the stators are generally circular and each comprises a pair of flat discs in spaced relation.

4. The receptacle of claim 3 wherein the openings at the peripheries of the stators are substantially continuous.

5. The receptacle of claim 3 wherein the stators are closely adjacent the respective closures.

6. The receptacle of claim 1 including a housing for the drum and means between the drum and housing forminga flue for the products of cornbustion of the burner.

7. The receptacle of claim 6 wherein the burner is located adjacent the liquid inlet, the flue having an entrance adjacent the outlets.

8. The receptacle of claim 1 including radial baffles in the drum adjacent the wall thereof.

9. The receptacle of claim 8 including apertured circumferential baffles in the drum intersecting the radial baffles.

10. The receptacle of claim 1 wherein the stators each comprise a pair of spaced plates located in generally transverse planes relative to the axis of the drum.

11. The receptacle of claim 10 including vanes be tween the plates of both the stators, said vanes assisting liquid flow into and out of the drum. 

1. A liquid receptacle comprising a rotary cylindrical drum, said drum comprising a wall, closures for the drum at each end of the wall, means to rotate the drum, a liquid outlet and a liquid inlet for the drum, an inlet stator in the drum between the axis of tHe drum and the wall thereof, an outlet stator in the drum between the axis of the drum and the same wall thereof, the stators being open at their peripheries to provide for flow of liquid there-through; the outlet stator periphery being closer to the wall than the inlet stator, the rotation of the drum causing liquid in the drum to form a ring along the drum wall, the stators being normally submerged at their outer peripheries within the ring of liquid, a fuel burner in the drum, the burner being arranged to project a flame at least partially directly against the ring of liquid.
 2. The receptacle of claim 1 including a blower wheel on the drum adjacent the outlet.
 3. The receptacle of claim 1 wherein the stators are generally circular and each comprises a pair of flat discs in spaced relation.
 4. The receptacle of claim 3 wherein the openings at the peripheries of the stators are substantially continuous.
 5. The receptacle of claim 3 wherein the stators are closely adjacent the respective closures.
 6. The receptacle of claim 1 including a housing for the drum and means between the drum and housing forming a flue for the products of combustion of the burner.
 7. The receptacle of claim 6 wherein the burner is located adjacent the liquid inlet, the flue having an entrance adjacent the outlets.
 8. The receptacle of claim 1 including radial baffles in the drum adjacent the wall thereof.
 9. The receptacle of claim 8 including apertured circumferential baffles in the drum intersecting the radial baffles.
 10. The receptacle of claim 1 wherein the stators each comprise a pair of spaced plates located in generally transverse planes relative to the axis of the drum.
 11. The receptacle of claim 10 including vanes between the plates of both the stators, said vanes assisting liquid flow into and out of the drum. 